Carpenter Ants in Canada: How to Identify, Prevent, and Eliminate Them

What Are Carpenter Ants?

Carpenter ants are among the most common pest ants found in Canada. The two primary species include the black carpenter ant (entirely dark brown to black) and the red carpenter ant, which features a reddish-brown upper body with a darker lower body.

These ants vary in size from 6 to 25 mm (0.24 to 1 inch) and are easily recognized by their narrow waist, bent antennae, and a three-segment body. During mating season, male and female carpenter ants develop wings, which often leads to them being mistaken for termites.

Why Carpenter Ants Are a Problem

Carpenter ants are known to cause structural damage to buildings by burrowing into wood to build their nests. Unlike termites, they do not eat wood—instead, they excavate it to create tunnels called galleries, leaving behind sawdust-like shavings.

Indoors, they are also a nuisance pest as they forage for sweet or protein-rich foods, including household crumbs and pet food. Outdoors, they feed on other insects and honeydew from aphids.

Carpenter Ants vs Termites: Key Differences

It’s common to confuse carpenter ants with termites, but they can be distinguished by:

Feature Carpenter Ants Termites

Waist Narrow (pinched) Thick, straight

Antennae Bent/elbowed Straight

Wings (if present) Unequal in size  Equal size

Color Black or reddish-brown White or pale beige

Note: Termites are only found in certain regions of Canada.

Signs of a Carpenter Ant Infestation

Watch for these common signs of carpenter ant activity in your home or yard:

• Sawdust-like debris (frass) near baseboards, windows, or walls
  
  

• Slit-like openings in wooden structures
  
  

• Rustling or dry tapping sounds within walls (most noticeable at night)
  
  

• Winged ants (swarmers) indoors, especially in spring
  
  

• Visible foraging trails, often leading outdoors
  
  

• High moisture areas like under sinks, in wall voids, or in basements
  
  

Where Carpenter Ants Nest

Carpenter ants prefer moist, decaying wood, but may also establish colonies in:

• Wall voids and attic spaces
  
  

• Wooden window sills and trim
  
  

• Behind drawers, bookshelves, and in hollow doors
  
  

• Insulation (including styrofoam)
  
  

• Firewood stored indoors or against the house
  
  

• Wooden porches or sheds attached to the home
  
  

They often create satellite colonies inside buildings, while the main (parent) colony remains outdoors in stumps, logs, or dead trees.

🧰 How to Get Rid of Carpenter Ants

✅ Physical Prevention & Control

• Remove decaying wood and firewood near or inside your home
  
  

• Seal cracks in foundations, siding, and window frames
  
  

• Trim vegetation away from the house (ants use branches to access roofs and walls)
  
  

• Correct moisture problems (leaky pipes, poor ventilation, damp basements)
  
  

• Replace infested or rotting wood with treated or dry material
  
  

• Store food securely in sealed containers
  
  

• Keep floors and counters clean of crumbs and spills
  
  

🧪 Chemical & Bait Control

⚠️ Always choose products with a Pest Control Products (PCP) number approved by Health Canada.

• Use ant baits with slow-acting poisons like boric acid, allowing workers to carry the bait back to the colony
  
  

• Apply insecticidal dusts to wall voids or entry points (ensure it is safe for indoor use)
  
  

• For exterior control, apply chemical barriers to entry points, siding gaps, or around foundations
  
  

• Never spray directly during baiting—sprays can scatter the colony and reduce bait effectiveness
  
  

• Leave dead ants in place during treatment—scavengers will carry poisoned bodies back to the colony
  
  

For food preparation areas, only use products labelled safe for kitchens and food handling areas, and follow all instructions carefully.

🧑‍🔧 When to Call a Pest Control Professional

If carpenter ants have established a satellite nest indoors or you're unable to locate the main colony, professional pest control services may be necessary. Licensed experts use advanced techniques like:

• Moisture detection tools
  
  

• Thermal imaging cameras
  
  

• Targeted insecticides and dusts
  
  

• Long-term exclusion strategies
  
  

Professional exterminators can help ensure the entire colony is eliminated, reducing the risk of recurring infestations.

🏡 Final Tips for Carpenter Ant Control in Canada

• Regularly inspect your home for moisture damage and signs of activity
  
  

• Fix leaks and ventilation issues immediately
  
  

• Monitor spring and summer seasons closely when ants are most active
  
  

• Educate yourself on carpenter ant behavior to prevent costly damage